Completed sections on backup, remotes, lab notebook, and collaboration.
fixed several typos.
updated figures to higher resolution versions.
updated bibliography
Added new workflow diagram

New figure (now figure 1) shows a conceptual workflow involving 3 hypothetical coauthors and possible revisions that might occur over the course of a project.
Revised abstract and introduction

Abstract is more concise and I fleshed out the distinction between CVCS and DVCS to make it clear why git is better for science.
Generated new pdf with updated figures.